[PATCH v2] powerpc/64s: Add dt_cpu_ftrs boot time setup option

[Michael Ellerman]

Nicholas Piggin <npiggin at gmail.com> writes:

> On Tue, 30 May 2017 16:28:09 +1000
> Michael Ellerman <mpe at ellerman.id.au> wrote:
>
>> From: Nicholas Piggin <npiggin at gmail.com>
>> 
>> Provide a dt_cpu_ftrs= cmdline option to disable the dt_cpu_ftrs CPU
>> feature discovery, and fall back to the "cputable" based version.
>> 
>> Also allow control of advertising unknown features to userspace and
>> with this parameter, and remove the clunky CONFIG option.
>> 
>> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
>> [mpe: Add explicit early check of bootargs in dt_cpu_ftrs_init()]
>
> Thanks for fixing that up. The patch is more yours than mine now :P
>
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -866,6 +866,16 @@
>>  
>>  	dscc4.setup=	[NET]
>>  
>> +	dt_cpu_ftrs=	[PPC]
>> +			Format: {"off" | "known"}
>> +			Control how the dt_cpu_ftrs device-tree binding is
>> +			used for CPU feature discovery and setup (if it
>> +			exists).
>> +			off: Do not use it, fall back to legacy cpu table.
>> +			known: Do not pass through unknown features to guests
>> +			or userspace, only those that the kernel is not aware
>> +			of.
>
> Well that's not the right number of nots. Better make it:
>
> +			known: Do not pass through unknown features to guests
> +			or userspace, only those that the kernel is not not
> +			aware of.

My snot-filled sleep-deprived brain nearly merged that as-is :D

cheers